3.1.6 ATP

3.1.6 ATP

1. Structure + synthesis of ATP

   • Structure
     • Nitrogenous base
       • Adenine
     • Pentose sugar
       • Ribose
         • Adeosine
     • 3 phosphate groups
   • Synthesis
     • ATP + Water ↔ ADP + Pi
     • → ATP hydrolase
     • ATP Synthase ←
       • Enzyme
     • Inorganic Phosphate
     • Where synthesis of ATP used?
       • Photophosphorylation
         • w/aid of light
         • in chlorophyll containing plant cells
       • Oxidative phosphorylation
         • Use of O₂
         • In plant/animal cells during respiration
       • substrate-level phosphorylation
         • In plant/animal cells
         • Phosphate groups transferred from donor molecules to ADP

2. Why does ATP release so much energy when hydrolysed?

   • Phosphate groups are negatively charged (-)
     • The bonds between the phosphate groups are under tension
       • As opposites attract The same rebel
         • ∴ bonds between the groups are "unstable"
           • ∴ lower the activation energy required to break bonds
             • ∴ bonds are easily broken

3. High turnover of ATP

   • ATP is constantly being synthesised
   • Used constantly
   • Why has ATP have a high turnover?
     • Short term energy molecule
       • Unstable bonds - bad longterm storage
       • "Immediate energy source"

4. Why use ATP and not other molecules? (e.g Glucose)

   • ATP releases small quantities of energy
     • Glucose would release too much energ
   • One step process to hydrolyse ATP
     • Glucose requires a lot more steps
   • Stores need to be replenished by mitochondria

5. More active tissues = more mitochondria

   • Metabolic processes
     • Building Macromolecules e.g Starch
   • Movement
     • Muscle contraction